This invention relates to a synergistic surfactant composition formed by combining an alkylbenzenesulfonate anionic surfactant with at least one organic zwitterionic functional silicone zwitterionic surfactant represented by the formula: EQU Me.sub.3 SiO[SiMe.sub.2 O].sub.x [SiMeR.sup.1 O].sub.y SiMe.sub.3
and wherein:
Me=methyl; PA1 R.sup.1 =CH.sub.2 CH.sub.2 CH.sub.2 N.sup.+ (R.sup.2).sub.2 (CH.sub.2).sub.z SO.sub.3.sup.- ; PA1 R.sup.2 =methyl or ethyl; PA1 x=0-3; PA1 y=1-2; and PA1 z=3-4. PA1 Me=methyl; PA1 R.sup.1 =CH.sub.2 CH.sub.2 CH.sub.2 N(R.sup.2).sub.2 (CH.sub.2).sub.z SO.sub.3.sup.- ; PA1 R.sub.2 =methyl or ethyl; PA1 x=0-3; PA1 y=1-2; and PA1 z=3-4. PA1 Me=methyl; PA1 R.sup.1 =CH.sub.2 CH.sub.2 CH.sub.2 N(R.sup.2).sub.2 (CH.sub.2).sub.z SO.sub.3.sup.-1 ; PA1 R.sup.2 =methyl or ethyl; PA1 x=0-3; PA1 y=1-2; and PA1 z=3-4. PA1 Me=methyl; PA1 R.sup.1 =CH.sub.2 CH.sub.2 CH.sub.2 N(R.sup.2).sub.2 (CH.sub.2).sub.z SO.sub.3.sup.- ; PA1 R.sup.2 =methyl or ethyl; PA1 x=0-3; PA1 y=1-2; and PA1 z=3-4 PA1 Me=methyl; PA1 R.sup.1 =CH.sub.2 CH.sub.2 CH.sub.2 N(R.sup.2).sub.2 (CH.sub.2).sub.z SO.sub.3.sup.-1 ; PA1 R.sup.2 =methyl or ethyl; PA1 x=0-3; PA1 y=1-2; and PA1 z=3-4
More particularly, the zwitterionic surfactants are represented by the following formulas: ##STR2##
A surfactant is a compound that reduces surface tension when dissolved in a liquid decreasing the attractive force exerted by molecules below the surface of the liquid upon those molecules at the surface of the liquid enabling the liquid to flow more readily. Liquids with low surface tensions flow more readily than water, while mercury with the highest surface tension of any liquid does not flow but disintegrates into droplets.
Surfactants exhibit combinations of cleaning, detergency, foaming, wetting, emulsifying, solubilizing, and dispersing properties. They are classified depending upon the charge of the surface active moiety, usually the larger part of the molecule. In anionic surfactants, the moiety carries a negative charge as in soap. In cationic surfactants, the charge is positive. In non-ionic surfactants, there is no charge on the molecule, and in amphoteric surfactants, solubilization is provided by the presence of positive and negative charges in the molecule.
Zwitterionic surfactants of the type disclosed herein are generally considered specialty surfactants. They do not irritate skin and eyes, and exhibit good surfactant properties over a wide pH range. This category of surfactant is compatible with anionic, cationic, and nonionic surfactants, and the use of these amphoteric surfactants ranges from detergents, emulsifiers, wetting and hair conditioning agents, foaming agents, fabric softeners, to anti-static agents. In cosmetic formulations, certain specialized zwitterionic surfactants reduce eye irritation caused by sulfate and sulfonate surfactants present in such products.
In U.S. Pat. No. 3,562,786, issued Feb. 9, 1971, to Bailey et al, there is disclosed the broad concept of blending organic surfactants with silicone-glycol type surfactants in order to achieve a synergy. The surfactants in Bailey et al, however, are generally considered to be of the standard non-ionic silicone type, rather than amphoteric, as in the present invention. Thus, in contrast to Bailey et al, the present invention blends organic surfactants with a new class of silicone sulfobetaine zwitterionic surfactants in order to achieve a synergistic effect. The sulfobetaine surfactants of the present invention, because they are a new class of silicone surfactant, possess advantages not inherent in Bailey et al. For example, one would not expect a zwitterionic surfactant to perform in the same fashion as a non-ionic surfactant as in Bailey et al because of the differences in the charged natures of the two categories of surfactants. Further, the zwitterionic surfactants of the present invention are solids and have a low water solubility in comparison to the Bailey et al liquid surfactants which are very water soluble. In addition, the zwitterionic surfactants of the present invention possess much lower critical micelle concentrations than the non-ionic surfactants in Bailey et al.
Such disadvantages of the prior art are overcome with the present invention wherein not only is a new class of silicone surfactant disclosed but a surfactant that possesses synergistic properties when combined with organic surfactants.